The present invention relates generally to navigational systems and devices, and in particular to PDA systems and PDA devices having functional data, and methods to pack and unpack n-dimensional data associated with cartographic data.
In a variety of applications, geographic features can be represented by coordinate sets and stored in computer data stores in the form of bits representing the coordinate information. The coordinate information often requires a large amount of storage space on the medium that is used to store it. This always presents a significant problem and becomes particularly undesirable when the storage medium has limited capacity that may not be sufficient to handle the data that must be stored.
The coordinate sets are included within cartographic data that is accessible to a navigational aid device. Further, the cartographic data is loaded into a memory of the device and manipulated to provide route planning and other features to a user of the device. Cartographic data includes, by way of example only, coordinate sets, thoroughfare identifications, intersection identifications, altitude information, depth information, landmark information, shoreline information, marine information, aeronautical information, longitude information, latitude information and the like. Cartographic data is voluminous and as a result, often only specific cartographic data associated with predefined geographic regions is loaded into the device during any particular operation cycle. Moreover, devices utilizing the cartographic data often have limited memory capacity and processing throughput. Accordingly, cartographic data is packed or compressed to achieve more efficient usage of limited memory resources.
In a variety of applications, geographic features are typically represented by coordinate sets and stored in data stores in the form of bits representing the coordinate information. The coordinate information often requires a large amount of storage space on the medium that is used to store it. This presents a significant problem and becomes particularly undesirable when the storage medium has limited storage capacity that may not be sufficient to handle the data that must be stored.
Polyline and polygon features can be represented by starting coordinate sets, each set representing a dimension within the cartographic data, and coordinate changes between successive coordinate sets. Generally, cartographic features vary widely in data size and shape, and some features have large changes in the coordinates while others have only small changes. It is not uncommon, especially with man-made structures, for a feature to have large ranging changes in one coordinate direction and only small changes in another direction. For example, roadways and grids of streets often follow north-south or east-west paths. Other features, both natural and man-made, exhibit similar characteristics.
Optimally packing coordinate set data has been established, such as Method and Apparatus for Geographic Coordinate Data Storage by Robinson et al., U.S. Pat. No. 5,995,970 (xe2x80x9cRobinsonxe2x80x9d) commonly assigned to the Garmin Corporation. Robinson is directed to packing coordinate data along two geographic dimensions associated with a coordinate set of x and y (e.g., longitude and latitude).
Furthermore, packing more than two dimensions to include a third dimension, which is directly associated with one of the two packed dimensions, can provide tremendous benefits. For example, consider a marine vehicle traveling along a marked waterway (e.g., a recommended route) and using a navigational device which includes packed cartographic data. The cartographic data represents the path of the recommended route using longitude and latitude coordinates (two dimensions). However, the marine vehicle can benefit by having cartographic data which also includes data identifying water depth (e.g., third dimension) along the recommended route and perhaps bottom conditions (e.g., four or more dimensions) along the recommended route. Therefore, not all cartographic data is used to represent only two dimensions. Accordingly, a need exists to pack more than two dimensions in cartographic data and a need exists to identify which dimensions need to be packed within the cartographic data.
In summary, current prior art systems do not efficiently pack or use cartographic data associated with three or more dimensions. As users demand navigational products with greater informational capabilities, the problem will continue to escalate. Additionally, present devices which do not pack cartographic data in more than two dimensions and which do not provide for the ability to activate and deactivate dimensions do not adequately provide the ability to add greater content to the cartographic data in a space efficient and user configurable manner.
Therefore, there exists a need for a navigational device that more efficiently configures, packs, and uses cartographic data having more than two dimensions. Moreover, there is also a need for a navigational device which can process and unpack cartographic data using only dimensions desired by a user of the navigation device.
The above mentioned problems of navigational devices are addressed by the present invention and will be understood by reading and studying the following specification. Systems, devices, functional data, and methods are provided to pack n-dimensional data. The systems, devices, functional data, and methods of the present invention offer a device having n-dimensional data packing and unpacking capabilities. The device is capable of efficiently and accurately packing and unpacking of n-dimensional data.
In one embodiment of the present invention, a method to pack three or more dimensions represented in cartographic data is provided wherein cartographic data is received having dimension control data operable to represent one or more coordinated data. Each coordinate data has three or more dimensional data. Further, the coordinate data and the control data are packed into the cartographic data where each dimensional data associated with each coordinate data are compressed into an optimal size. Additionally, one or more special data are used to represent at least one dimensional data having a length exceeding the optimal size for the at least one dimensional data permitting the coordinate data to be compressed into the optimal size.
In another embodiment of the present invention functional data to configure and use attribute data is provided including activation data operable to activate or deactivate one or more attributes associated with the attribute data. Moreover, the functional data includes packed data representing compressed activation data and compressed attribute data. Further, the functional data includes instruction data to decompress the activation data and the attribute data. Also, the instruction data decompresses the activation data by using the attribute data, which indicates whether one or more of the attributes are activated in the activation data.
These and other embodiments, aspects, advantages, and features of the present invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art by reference to the following description of the invention and referenced drawings or by practice of the invention. The embodiments, aspects, advantages, and features of the invention are realized and attained by means of the instrumentalities, procedures, and combinations particularly pointed out in the appended claims.